N-(3,5-dimethoxyphenyl)-N′-(1-methylethyl)-N-[3-(1-methyl-1H-pyrazol-4-yl)quinoxalin-6-yl]ethane-1,2-diamine (compound A) is represented by the following formula

N-(2-fluoro-3,5-dimethoxyphenyl)-N-(1H-imidazol-2-ylmethyl)-3-(1-methyl-1H-pyrazol-4-yl)pyrido[2,3-b]pyrazin-6-amine (compound B) is represented by the following formula

Compounds N-(3,5-dimethoxyphenyl)-N′-(1-methylethyl)-N-[3-(1-methyl-1H-pyrazol-4-yl)quinoxalin-6-yl]ethane-1,2-diamine (compound A) or a pharmaceutically acceptable salt thereof or a solvate thereof, and N-(2-fluoro-3,5-dimethoxyphenyl)-N-(1H-imidazol-2-ylmethyl)-3-(1-methyl-1H-pyrazol-4-yl)pyrido[2,3-b]pyrazin-6-amine (compound B) or a pharmaceutically acceptable salt thereof or a solvate thereof, and their chemical synthesis are described in WO2011/135376 and WO2013/061080, which are incorporated herein by reference. They are described as inhibitors or modulators of the activity of certain protein tyrosine kinases, in particular FGFR, and thus the compounds are useful in the treatment or prophylaxis, in particular the treatment, of disease states or conditions mediated by those tyrosine kinases, in particular FGFR. The compounds are useful in the treatment or prophylaxis, in particular the treatment, of cancer.
In WO2011/135376 present compound A is also exemplified as a hydrochloride salt. In WO2013/061080 present compound B is also exemplified as a sulfate salt, as a hydrochloride salt, as a phosphate salt, as a lactate salt, as a fumarate salt.
FGFR
The fibroblast growth factor (FGF) family of protein tyrosine kinase (PTK) receptors regulates a diverse array of physiologic functions including mitogenesis, wound healing, cell differentiation and angiogenesis, and development. Both normal and malignant cell growth as well as proliferation are affected by changes in local concentration of FGFs, extracellular signalling molecules which act as autocrine as well as paracrine factors. Autocrine FGF signalling may be particularly important in the progression of steroid hormone-dependent cancers to a hormone independent state. FGFs and their receptors are expressed at increased levels in several tissues and cell lines and overexpression is believed to contribute to the malignant phenotype. Furthermore, a number of oncogenes are homologues of genes encoding growth factor receptors, and there is a potential for aberrant activation of FGF-dependent signalling in human pancreatic cancer (Knights et al., Pharmacology and Therapeutics 2010 125:1 (105-117); Korc M. et al Current Cancer Drug Targets 2009 9:5 (639-651)).
The two prototypic members are acidic fibroblast growth factor (aFGF or FGF1) and basic fibroblast growth factor (bFGF or FGF2), and to date, at least twenty distinct FGF family members have been identified. The cellular response to FGFs is transmitted via four types of high affinity transmembrane protein tyrosine-kinase fibroblast growth factor receptors (FGFR) numbered 1 to 4 (FGFR1 to FGFR4).
Disruption of the FGFR1 pathway should affect tumor cell proliferation since this kinase is activated in many tumor types in addition to proliferating endothelial cells. The over-expression and activation of FGFR1 in tumor-associated vasculature has suggested a role for these molecules in tumor angiogenesis.
A recent study has shown a link between FGFR1 expression and tumorigenicity in Classic Lobular Carcinomas (CLC). CLCs account for 10-15% of all breast cancers and, in general, lack p53 and Her2 expression whilst retaining expression of the oestrogen receptor. A gene amplification of 8p12-p11.2 was demonstrated in ˜50% of CLC cases and this was shown to be linked with an increased expression of FGFR1. Preliminary studies with siRNA directed against FGFR1, or a small molecule inhibitor of the receptor, showed cell lines harbouring this amplification to be particularly sensitive to inhibition of this signalling pathway. Rhabdomyosarcoma (RMS) is the most common pediatric soft tissue sarcoma likely results from abnormal proliferation and differentiation during skeletal myogenesis. FGFR1 is over-expressed in primary rhabdomyosarcoma tumors and is associated with hypomethylation of a 5′ CpG island and abnormal expression of the AKT1, NOG, and BMP4 genes. FGFR1 has also been linked to squamous lung cancer, colorectal cancer, glioblastoma, astrocytomas, prostate cancer, small cell lung cancer, melanoma, head and neck cancer, thyroid cancer, uterine cancer.
Fibroblast growth factor receptor 2 has high affinity for the acidic and/or basic fibroblast growth factors, as well as the keratinocyte growth factor ligands. Fibroblast growth factor receptor 2 also propagates the potent osteogenic effects of FGFs during osteoblast growth and differentiation. Mutations in fibroblast growth factor receptor 2, leading to complex functional alterations, were shown to induce abnormal ossification of cranial sutures (craniosynostosis), implying a major role of FGFR signalling in intramembraneous bone formation. For example, in Apert (AP) syndrome, characterized by premature cranial suture ossification, most cases are associated with point mutations engendering gain-of-function in fibroblast growth factor receptor 2. In addition, mutation screening in patients with syndromic craniosynostoses indicates that a number of recurrent FGFR2 mutations accounts for severe forms of Pfeiffer syndrome. Particular mutations of FGFR2 include W290C, D321A, Y340C, C342R, C342S, C342W, N549H, K641R in FGFR2.
Several severe abnormalities in human skeletal development, including Apert, Crouzon, Jackson-Weiss, Beare-Stevenson cutis gyrata, and Pfeiffer syndromes are associated with the occurrence of mutations in fibroblast growth factor receptor 2. Most, if not all, cases of Pfeiffer Syndrome (PS) are also caused by de novo mutation of the fibroblast growth factor receptor 2 gene, and it was recently shown that mutations in fibroblast growth factor receptor 2 break one of the cardinal rules governing ligand specificity. Namely, two mutant splice forms of fibroblast growth factor receptor, FGFR2c and FGFR2b, have acquired the ability to bind to and be activated by atypical FGF ligands. This loss of ligand specificity leads to aberrant signalling and suggests that the severe phenotypes of these disease syndromes result from ectopic ligand-dependent activation of fibroblast growth factor receptor 2.
Genetic aberrations of the FGFR3 receptor tyrosine kinase such as chromosomal translocations or point mutations result in ectopically expressed or deregulated, constitutively active, FGFR3 receptors. Such abnormalities are linked to a subset of multiple myelomas and in bladder, hepatocellular, oral squamous cell carcinoma and cervical carcinomas. Accordingly, FGFR3 inhibitors would be useful in the treatment of multiple myeloma, bladder and cervical carcinomas. FGFR3 is also over-expressed in bladder cancer, in particular invasive bladder cancer. FGFR3 is frequently activated by mutation in urothelial carcinoma (UC). Increased expression was associated with mutation (85% of mutant tumors showed high-level expression) but also 42% of tumors with no detectable mutation showed over-expression, including many muscle-invasive tumors. FGFR3 is also linked to endometrial and thyroid cancer. Over expression of FGFR4 has been linked to poor prognosis in both prostate and thyroid carcinomas. In addition a germline polymorphism (Gly388Arg) is associated with increased incidence of lung, breast, colon, liver (HCC) and prostate cancers. In addition, a truncated form of FGFR4 (including the kinase domain) has also been found to be present in 40% of pituitary tumours but not present in normal tissue. FGFR4 overexpression has been observed in liver, colon and lung tumours. FGFR4 has been implicated in colorectal and liver cancer where expression of its ligand FGF19 is frequently elevated. FGFR4 is also linked to astrocytomas, rhabdomyosarcoma.
Fibrotic conditions are a major medical problem resulting from abnormal or excessive deposition of fibrous tissue. This occurs in many diseases, including liver cirrhosis, glomerulonephritis, pulmonary fibrosis, systemic fibrosis, rheumatoid arthritis, as well as the natural process of wound healing. The mechanisms of pathological fibrosis are not fully understood but are thought to result from the actions of various cytokines (including tumor necrosis factor (TNF), fibroblast growth factors (FGF's), platelet derived growth factor (PDGF) and transforming growth factor beta. (TGFβ) involved in the proliferation of fibroblasts and the deposition of extracellular matrix proteins (including collagen and fibronectin). This results in alteration of tissue structure and function and subsequent pathology.
A number of preclinical studies have demonstrated the up-regulation of fibroblast growth factors in preclinical models of lung fibrosis. TGFβ1 and PDGF have been reported to be involved in the fibrogenic process and further published work suggests the elevation of FGF's and consequent increase in fibroblast proliferation, may be in response to elevated TGFβ1. The potential therapeutic benefit of targeting the fibrotic mechanism in conditions such as idiopathic pulmonary fibrosis (IPF) is suggested by the reported clinical effect of the anti-fibrotic agent pirfenidone. Idiopathic pulmonary fibrosis (also referred to as Cryptogenic fibrosing alveolitis) is a progressive condition involving scarring of the lung. Gradually, the air sacs of the lungs become replaced by fibrotic tissue, which becomes thicker, causing an irreversible loss of the tissue's ability to transfer oxygen into the bloodstream. The symptoms of the condition include shortness of breath, chronic dry coughing, fatigue, chest pain and loss of appetite resulting in rapid weight loss. The condition is extremely serious with approximately 50% mortality after 5 years.
As such, the compounds which inhibit FGFR will be useful in providing a means of preventing the growth or inducing apoptosis in tumours, particularly by inhibiting angiogenesis. It is therefore anticipated that the compounds will prove useful in treating or preventing proliferative disorders such as cancers. In particular tumours with activating mutants of receptor tyrosine kinases or upregulation of receptor tyrosine kinases may be particularly sensitive to the inhibitors. Patients with activating mutants of any of the isoforms of the specific RTKs (receptor tyrosine kinases) discussed herein may also find treatment with RTK inhibitors particularly beneficial.
The FGFR kinase inhibitors described herein have a differentiated selectivity profile which provides a new opportunity to use these targeted agents in patient sub-groups whose disease is driven by FGFR deregulation. The FGFR kinase inhibitors described herein exhibit reduced inhibitory action on additional kinases, particularly VEGFR, more in particular VEGFR2, and PDGFR, in particular PDGFR-beta, and offer the opportunity to have a differentiated side-effect or toxicity profile and as such allow for a more effective treatment of these indications Inhibitors of VEGFR2 and PDGFR-beta are associated with toxicities such as hypertension or oedema respectively. In the case of VEGFR2 inhibitors this hypertensive effect is often dose limiting, may be contraindicated in certain patient populations and requires clinical management.
Vascular Endothelial Growth Factor Receptor (VEGFR)
Vascular endothelial growth factor (VEGF), a polypeptide, is mitogenic for endothelial cells in vitro and stimulates angiogenic responses in vivo. VEGF has also been linked to inappropriate angiogenesis. VEGFR(s) are protein tyrosine kinases (PTKs). PTKs catalyze the phosphorylation of specific tyrosine residues in proteins involved in cell function thus regulating cell growth, survival and differentiation.
Three PTK receptors for VEGF have been identified: VEGFR-1 (Flt-1); VEGFR-2 (Flk-1 or KDR) and VEGFR-3 (Flt-4). These receptors are involved in angiogenesis and participate in signal transduction. Of particular interest is VEGFR-2, which is a transmembrane receptor PTK expressed primarily in endothelial cells. Activation of VEGFR-2 by VEGF is a critical step in the signal transduction pathway that initiates tumour angiogenesis. VEGF expression may be constitutive to tumour cells and can also be upregulated in response to certain stimuli. One such stimuli is hypoxia, where VEGF expression is upregulated in both tumour and associated host tissues. The VEGF ligand activates VEGFR-2 by binding with its extracellular VEGF binding site. This leads to receptor dimerization of VEGFRs and autophosphorylation of tyrosine residues at the intracellular kinase domain of VEGFR-2. The kinase domain operates to transfer a phosphate from ATP to the tyrosine residues, thus providing binding sites for signalling proteins downstream of VEGFR-2 leading ultimately to initiation of angiogenesis.
PDGFR
A malignant tumour is the product of uncontrolled cell proliferation. Cell growth is controlled by a delicate balance between growth-promoting and growth-inhibiting factors. In normal tissue the production and activity of these factors results in differentiated cells growing in a controlled and regulated manner that maintains the normal integrity and functioning of the organ. The malignant cell has evaded this control; the natural balance is disturbed (via a variety of mechanisms) and unregulated, aberrant cell growth occurs. A growth factor of importance in tumour development is the platelet-derived growth factor (PDGF) that comprises a family of peptide growth factors that signal through cell surface tyrosine kinase receptors (PDGFR) and stimulate various cellular functions including growth, proliferation, and differentiation.
cMet
The hepatocyte growth factor (HGF) (also known as scatter factor) receptor, c-Met (Met), is a receptor tyrosine kinase that regulates cell proliferation, morphogenesis, and motility. The c-Met gene is translated into a 170 kD protein that is processed into a cell surface receptor composed of a 140 kD β transmembrane subunit and 50 kD glycosylated extra cellular α subunit.
Mutations in c-Met, over-expression of c-Met and/or HGF/SF (scatter factor), expression of c-Met and HGF/SF by the same cell, and over-expression and/or aberrant c-Met signalling is present in a variety of human solid tumours and is believed to participate in angiogenesis, tumour development, invasion, and metastasis. Cell lines with uncontrolled c-Met activation, for example, are both highly invasive and metastatic. A notable difference between normal and transformed cells expressing c-Met receptor is that phosphorylation of the tyrosine kinase domain in tumour cells is often independent of the presence of ligand.
C-Met mutations/alterations have been identified in a number of human diseases, including tumours and cancers—for instance, hereditary and sporadic human papillary renal carcinomas, breast cancer, colorectal cancer optionally with liver metastases, gastric carcinoma, glioma, ovarian cancer, hepatocellular carcinoma, head and neck squamous cell carcinomas, testicular carcinoma, basal cell carcinoma, liver carcinoma, sarcoma, malignant pleural mesothelioma, melanoma, multiple myeloma, osteosarcoma, pancreatic cancer, prostate cancer, synovial sarcoma, thyroid carcinoma, non-small cell lung cancer (NSCLC) and small cell lung cancer, transitional cell carcinoma of urinary bladder, testicular carcinoma, basal cell carcinoma, liver carcinoma—and leukemias, lymphomas, and myelomas—for instance, acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), acute promyelocytic leukemia (APL), chronic lymphocytic leukemia (CLL), chronic myeloid leukemia (CML), chronic neutrophilic leukemia (CNL), acute undifferentiated leukemia (AUL), anaplastic large-cell lymphoma (ALCL), prolymphocytic leukemia (PML), juvenile myelomonocyctic leukemia (JMML), adult T-cell ALL, AML with trilineage myelodysplasia (AML/TMDS), mixed lineage leukemia (MLL), myelodysplastic syndromes (MDSs), myeloproliferative disorders (MPD), multiple myeloma, (MM), myeloid sarcoma, non-Hodgkin's lymphoma and Hodgkin's disease (also called Hodgkin's lymphoma).
Over-expression of c-Met is also believed to be a potentially useful predictor for the prognosis of certain diseases, such as, for example, breast cancer, non-small cell lung carcinoma, pancreatic endocrine neoplasms, prostate cancer, oesophageal adenocarcinoma, colorectal cancer, salivary gland carcinoma, diffuse large B-cell lymphoma and endometrial carcinoma.
Because of the role of aberrant HGF/SF-Met signalling in the pathogenesis of various human cancers, inhibitors of c-Met receptor tyrosine kinase have broad applications in the treatment of cancers in which Met activity contributes to the invasive/metastatic phenotype, including those in which c-Met is not over-expressed or otherwise altered. Inhibitors of c-Met also inhibit angiogenesis and therefore are believed to have utility in the treatment of diseases associated with the formation of new vasculature, such as rheumatoid arthritis and retinopathy.
WO2007/075567 and WO2008/155378, which are incorporated herein by reference, describe cMet inhibitors, such as 6-{difluoro[6-(1-methyl-1H-pyrazol-4-yl)[1,2,4]triazolo[4,3-b]pyridazin-3-yl]methyl}quinoline or a pharmaceutically acceptable salt thereof or a solvate thereof, and 6-[difluoro(6-pyridin-4-yl[1,2,4]triazolo[4,3-b]pyridazin-3-yl)methyl]quinoline or a pharmaceutically acceptable salt thereof or a solvate thereof, and their chemical synthesis, and polymorphs thereof. They are described as protein tyrosine kinase modulators, particularly inhibitors of c-Met, and the use of such compounds to reduce or inhibit kinase activity of c-Met in a cell or a subject, and modulate c-Met expression in a cell or subject, and the use of such compounds for preventing or treating in a subject a cell proliferative disorder and/or disorders related to c-Met, in particular cancer.
6-{Difluoro[6-(1-methyl-1H-pyrazol-4-yl)[1,2,4]triazolo[4,3-b]pyridazin-3-yl]methyl}quinoline (compound C) is represented by the following structure

6-[Difluoro(6-pyridin-4-yl[1,2,4]triazolo[4,3-b]pyridazin-3-yl)methyl]quinoline (compound D) is represented by the following formula

In WO2008/155378 crystalline forms and hydrates of compound C, in particular Form I, Form II, Form III, and a hydrate form of present compound C are also exemplified.
In WO2008/155378 present compound C is also exemplified as a HBr salt, as a HCl salt, as a methanesulphonate (mesylate) salt, as a ethanesulphonate (esylate) salt and as a p-toluenesulphonate (tosylate).
Compound C or a pharmaceutically acceptable salt thereof or a solvate thereof, and compound D or a pharmaceutically acceptable salt thereof or a solvate thereof, are selective cMet inhibitors.
WO2013/151913 relates to tyrosine kinase inhibitor combinations and their use.